Spin packs which are capable of spinning multiple component fibers are known, for example, through the above-cited Hills et al '074 and Hagen et al '650 patents. One problem that may exist, however, with conventional multiple component spin packs is premature spin pack down-time necessitated by plugging of filter elements associated with the polymer component having the higher throughput. That is, when spinning multiple component fibers, one or more of the individual polymer components (e.g., polymer components of different color) may have a greater spin pack throughput as compared to the spin pack throughput of other individual polymer components. Thus, while the filter elements adequately continue to filter that one (or more) individual polymer component having lesser spin pack throughput, the filter elements which filter the polymer component(s) having the greater polymer throughput have a propensity to clog thereby necessitating spin pack down time for service and/or cleaning. Also, some pigments require more filtration area than others even at the same throughputs.
According to the present invention, however, polymer throughputs of individual polymer components forming a multicomponent polymeric fiber are substantially equalized for purposes of filtration, even though the total throughput of one of the individual polymer components is greater/lesser as compared to the throughput of at least one other polymer component. That is, any unequal throughput of the polymer streams employed to form multiple polymer component yarn is, according to the present invention, equalized for purposes of polymer filtration within the spin pack.
More specifically, according to the present invention, at least two different individual polymeric fibers may be spun by directing at least two streams of different polymer melts (e.g., polymer melts of different colors) to a spin pack such that one of the streams has a greater volumetric throughput as compared to the volumetric throughput of the other stream. The polymer streams are each distributed within the spin pack among individual filtration chambers so that each such filtration chamber receives substantially the same volumetric throughput of the polymer melt streams. In such a manner, the polymer melt streams are distributed among the filtration chambers in substantially equal throughput allotments even though the total throughput of the melt streams of each of the different polymers may be different. The filtered polymer melt streams may then be directed through fiber-forming orifices of a spinneret plate to form the composite yarn.
These and other advantages of the invention will become more clear from the following detailed description of the preferred exemplary embodiment thereof which follows.